Process for conversion of hydrocarbons



Oct. 8, 1940. D. G. BRANDT PROCESS FOR CONVERSION 0F HYDROCARBONS Filed Aug. 13, 1937 T i X V M" g oww, ...096 m M m WB. NQ me, n Oeim A i w -1---- VM n Y .s E m. B ||I|| 52H2. ||II| llll ll.. QN Q.W\ ||l|| I l l I I I l l 1 u 1---- mw :1% H-- @sw llll l Emzwmrou HXI |l||| lll l' fil- -i l! Patented Oct. 8, 1940 UNITED STATES PATENT OFFICE David G. Brandt, Westfield, N. J., assignor to Power Patents Company, Hillside, N. J., a oorporation of Maine Application August 13, 1937, Serial No. 158,900

5 Claims.

This invention relates to a process for con' The process is particularly directed to an ixn-.

provement in the conversion of petroleum oil dis- 1 tillates into aromatic hydrocarbon products boiling within the gasoline'r'ange of boiling points. The products formed by the process when operated under specified conditions have been found .to contain relatively large proportions of alkylated ben'zenes boiling within the gasoline range.

The primary object of the present invention is to provide an improved process for the simultaneous treatment of relatively low boiling and relatively high boiling distillates (primarily outside the gasoline range) so as to make a conversion product of the gasoline boiling range which has a very high anti-knock value'.

Another object of the invention is to provide an improved process particularly adapted for the production of a mixture of polymerized unsaturated and aromatic hydrocarbons boiling within the gasoline range which has an octane number of 100 or higher.

A further object of the invention is to provide an improved process for making motor fuels suitable for blending with straight run gasolines or similar relatively low octane number fuels and to produce a high octane number motor fuel suitable for use in aircraft motors.

The improved process for the conversion of hydrocarbons in accordance with the features of the present invention includes the steps of simultaneously heating a distillate such as butane and a gas-oil distillate in separate heating zones in a pipe still furnace, heating the butane distillate to a substantially higher temperature and pressure than that to whichthe gas-oil is heated, mingling the products oi' both heating operations and subjecting the resulting mixture'to conversion conditions in the vapor phase to polymerize the constituents together while passing in va stream through a heating zone, and then continuing to subject the resulting cracked vapor I(Cl. 196-9) which illustrates atlcally `one form of apparatuswhich is adapted to carry out the improved process. v l The single figure ofthe drawing is amore Vor less conventional elevational view of assembled apparatus elements adapted to carry out, the process.

Referring to the drawing the high boiling feed vstock `which may be gas-oil or other distillate of higher boiling point than gasoline is introduced into the apparatus through a supply line 2 and forced by means of a pump 4, at a pressure of from 400 to about 600 lbs. per square inch through a line 6 and passed to a pipe still heater furnace 8 in which the oil is conducted through 15 a preheater coil I 0,`a connecting pipe I2 and a high temperature heating coil I4 which discharges through a line I6 into a mixing header I8. The distillate delivered to the preheating coil I0 may have been preheated to a temperature of `about 600 F. (for example in a preheating coil1 in the fractionating tower) so that it is further heated in the coil I0 to approximately 800 F. The heating in the coil I4 lpreferably raises the temperature of the oil to about 980 F. as it enters the line I8.

The light distillate charging stock such as propane, butane or pentane to be converted in accordance with the process of the present invention may comprise a mixture containing small proportions of lower boiling material as well as small proportions of higher boiling constituents but preferably is a butane fraction. This distillate is introduced into the system of the apparatus through a line 20 and forced by means of a pump 22 at apressure of from 600 to 1000 lbs. per square inch through a line 24 into the pipe still heater 8 and then past through a preheating coil 26 in which the distillate is preheated to a temperature of about 600 F. The preheated distillate is then conducted through a line 28 and passed through a radiant heating bank of tubes 30 where it is raised to a temperature of approximately 1125 F., at which temperature it is conducted through a line 32, containing a pressure control valve, and mixed with the products from the tube bank I 4 in the line I6 and mixing header I8. The mixing carried out in the line I6 and headerl IB should be suiilcient to substantially .equalize the temperature of the combinedproducts which are then passed through a bank of digestion tubes adapted to polymerize the combined products together and eii'ect conversion thereof to aromatic other high anti-knock hydrocarbons boiling within the gasoline range.

be able to carry out the operation in the digestion bank without a great pressure drop and at the l same time maintain the products at a relatively high velocity. The highly heated products heated in the coils 34 are dlscharged into 'fa large vapor line 38 at a temperature of abou't 1040 F. and introduced into the top of an enlarged vertical heat insulated reaction chamber 38 where the conversion reaction is continued while the vapors pass at relatively reduced velocity downwardly therethrough.

'I'he cracking accomplished in the coils I4 and 30 is preferably completed in as short a time as possible and at the same time produces a very substantial proportion of unsaturated hydrocarbons. 'I'he products from these coils, however, should be mixed in the header I8 before any substantial degree of polymerization has taken place in-the coils I4 and 30. The products discharged from the coils i4 and 30 may contain from 40 to 70% of unsaturated hydrocarbons which are preferably the primary products resulting from the cracking of the stocks passed through these coils. While some small amount of polymerization may occur during the formation of the unsaturated hydrocarbons in the coils I4 and 3B the operation should be carried out so that the products from these coils are polymerized with each other as quickly as possible after their formation by passing them through the coils 34 and chamber 38.

The pipe still heater furnace 8 shown diagrammatically in the drawing may be constructed substantialiy as shown so that the tube banks I4 and 80 are radiant heating banks heated by burners (not shown) mounted below and on each side of the heater. The products of combustion from the burners used for heating the banks I4 and 30 pass upwardly and around the refractory bridge walls and downwardly in contact with the digestion tubes of coils 34. Finally the products of combustion at substantially reduced temperature are utilized to heat the preheating banks I0 and 26. v

The enlarged tower 38 is divided into upper and lower sections by means of a funnel 40. The

reaction products in the upper reaction section' of the tower 38 are subjected to polymerizing l reactions at a temperature of about l010 F. and a pressure of from 200 to 300 lbs. per square inch. By the time these products reach the funnel 40 they will have completed the desired amount of conversion and are therefore suddenly chilled in order to avoid coke formation which usually occurs where such vapors are cooled slowly through the range of cracking temperatures. The sudden chilling may be effected by introducing water or oil drawn through a line 42 and forced by means of a pump 44 and a line 46 through a spray nozzle 48 directly into the funnel 40. Suiiicient water or other cooling uid is introduced into the vapors entering the funnel to quickly chill them to a temperature of about r100 to 750 F. and thereby cause condensation of certain high boiling tarlike materials which are produced in the conversion operation. These tar-like materials are collected in the bottom or separator section of the tower I8 and withdrawn therefrom through a float valve controlled line Il.

The cooling of the high temperature vapors in the funnel 48 to a temperature of about 700 to 750 F. removes the tarry constituents as referred to and leavesthe vapors relatively free from high boillngproducts. The separated vapors pass upwardly around the neck of the funnel 40 and are discharged through a valve controlled vapor -line 52 into the base of a fractionating tower I4 which is utilized for fractionating the cracked product and more particularly to separate the gasoline range boiling materials from constituents of higher boiling point. The gasoline constituents therefore pass from the tower 54 at a.v temperature of from 420 to 460 F. through a vapor line 5B which connects with the upper end of a plurality of vapor treating towers 58. The towers 58 may be used alternately and the resulting treated product passes therefrom through a line 80 `into the base of a second tower 82.

The towers 58 may be used as clay treaters for treating the gasoline vconstituents in the vapor phase, but they are preferably used for treating the gasoline vapors with phosphoric acid (85%) which is usually deposited in the towers on some convenient supporting material such as diatoms.- ceous earth, charcoal or coke. The towers may beused alternately so that one tower is cut out of the system f or cleaning and refilling while the other is being used. Phosphoric acid has been found to be, particularly desirable as a treating medium for refining the high anti-knock product produced bythe process of the present invention.

'Ihe gasoline constituents discharged through the line 80 usually contain certain higher boiling materials 'which are fractionated out in the tower 62; the high -boiling material being removed through a float valve controlled line 84 while the fractionated gasoline vapors free of undesirable higher boiling materials are discharged through a vapor line 68. The vapors discharged through the line 88 are condensed in a condenser 88 and the resulting condensate, together with the normally uncondensable gases are discharged into a receiver 10.

The pressure maintained in the tower 38 is preferably carried throughout the subsequent elements of the apparatus down to the gas separator 'I0 except for the natural pressure drop. The vapors condensed in the condenser 68 therefore are condensed under a considerable pressure so that the condensate separated out in the receiver 10 contains substantial proportions of relatively low boiling point constituents in the butane and propane range. The relatively dry gasses are discharged from the receiver 10 through an automatic pressure valve controlled line 12. The receiver 10 is also used as a water separator for the removal of water when it is introduced as a chilling medium in the tower 38. 'Ihis water is withdrawn through a valved line 14.

The high anti-knock gasoline produced in the process is withdrawn from receiver 10 through a line 16 and passed through a pump 'I8 and a Avalved line 80 into a gasoline stabilizer 82 which is operated at a pressure of from 25 to 50 pounds per square inch higher than the pressure in receiver 10, for fractlonating out and removing4 and propane. is withdrawn from the receiver 90 through a valved line 94 and any portion thereoi' desired for reflux in the top of the tower 82 is returned to the top of, the tower through a line 86 in which is mounted a circulatingpump. In therectication and stabilization of the gasoline product in the stabilizer 82, the excess butane and other condensed material is preferably taken through the line 84, or removed as a side stream distillate from tower 82, and conducted through a line 98 to the pump 22 and subjected to the conversion conditions in coils 30 and 34 maintained in the pipe still heater 8 and tower 38. This distillate which contains olens boiling in thel butane range, may comprise in part unconverted butane or other hy-I drocarbons supplied to the pipe still heater (after the process has once been placed in operation).

A portion of the gasoline product discharged from hpump 18 through the valved line 80 may be used as reux material in towers 54 and 62 by withdrawing regulated quantities of this material through a line and conducting a portion of it through a valved line |02 to the upper part of tower 62, and another portion through a valved line |04 to the upper part of vtower 54.

'I'he process of the present invention is particularly adapted for the treatment of diverse distillate stocks of the type referred to.` l In certain oil-producing districts the gas-o iland butane fractions of the petroleum produced are of little or no value except for lheating-purposes, unless they can be effectively converted into readily salable products such as high anti-knock gasoline. In such districts there is usually a large production of straight run gasoline of relatively low octane number so that a high octane number gasoline such as that produced by the process of the present invention is particularly desirable for blending purposes. The process therefore utilizes the butane and "gas-oil fractions of the petroleum or other distillates available under the conditions and converts them into a high octane blending stock which is particularly suited for blending with the straight `run gasoline normally produced from petroleum.

The gasoline product recovered through the line 84 under the conditions described may have an aromatic content lof as high as 80%. The aromatic compounds include benzol and toluol. but a large proportion of them are alkylated benzenes. Other polymerized hydrocarbons also contribute to the anti-knock value of the product.

The combined conversion operations involving the conversion of butane and gas-oil apparently involve a very substantial polymerizing operation by which the low molecular weight constituents, converted to active or nascent unsaturated hydrocarbons in the coil 30, are polymerized or combined with the higher boiling active unsaturated constituents from coil I4, in the coils 34 and chamber 38 to form high anti-knock and aromatic hydrocarbons and alkylate these aromatic hydrocarbons. The `long time digestion treatment at moderate vapor phase cracking temperatures and relatively high pressures (ior'vapor cracking) utilized in the coils 34 and chamber 3l appear to be the conditions which are responsible forthe production of the higher anti-knock product recovered.

While the process oi the present invention has been described somewhat specifically in connection with the production of a very high antiknock product it is to be understood that the process may be used for the 'production of a more or less ordinary cracked gasoline. A conversion to a gasoline product containing yfrom ,iifty percent or more of aromatic hydrocarbons is ordinarily desirable but an increase in the charging rate of the distillate stockssupplied to the pipe still furnace or. in the temperatures to which they are heated in the furnace orboth will reduce the aromatic content of the final product, and ordinarily the economy 'of operation. 'I'he process of the present invention is understood not to be limited to the specic dis- ,closure and examples given except by the claims which define the scope of the invention.

Having thus described the invention in its prei'erred form, what is claimed as new is: f

1. The process of manufacturing a high antiknock motor fuel product boiling within the gasoline range, which comprises simultaneously heating a butane distillate and a gas-oil distillate in separate heating zones in a pipe still furnace, heating the butane distillate in a stream of restricted cross-section to a temperature of approximately 1125 F., heating the gas-oil distillate in a separate stream of restricted cross-section to a temperature of approximately 980 F., heating said butane and said gas oil in said streams for a sufcient time to produce a substantial proportion of activel ornascent unsaturated hydrocarbons without substantially polymerizing the products of said streams therein, mixing the resulting highly heated products and.y thereafter heating the resulting mixture in the vapor phase yin a stream of restricted cross-section for a substantial'period of time at a temperature of approximately 1040 F., thereafter conducting the products of the mixed stream 'into an enlarged reaction zone and passing the same therethrough at a greatly reduced velocity, maintaining a temperature of approximately 1000 F. in said enlarged zona,v discharging the resulting highly heated converted products from said enlarged zone and as said products discharge therefrom quickly reducing their temperature to approximately 700 F. by intimately mingling a relatively cool cooling fluid therewith, thereby to ,condense out any relatively high boiling tarry materials contained in the vapor products discharged from said enlarged reaction zone, and fractionating the uncondensed vapors from said cooling operation to recover the high anti-knock motor fuel fraction.- 0

2. The improvement. in the art of converting hydrocarbons for `the production of a high antiknock gasoline, which comprises simultaneously heating a butane distillate and a gas-oil distillate in separate heating zones, heating the butane distillate in a stream of restricted cross-section to a substantially higher temperature than that to which said gas-oil distillate is heated to convert the constituents of the butane distillate into unsaturated compounds, heating the gas-oil distillate to a relatively high cracking temperature, mixing the products of said heating operations and subjecting the resulting mixture to a further heating at a temperature of approximately 1040 F. for a substantial period of .time to inter-polymerize the mixed products. conducting the resulting highly heated vapor products into an enlarged reaction -zone vin which the reaction is continued for a sufncient time to convert a substantial proportion of the products into constituents boiling within the gasoline range,fraction ating the resulting converted products to separate out a vapor fraction containing the desirable high anti-knock constituents, and intimately contacting this vapor fraction with a phosphoric 10 acid refining agent and recovering the resulting products.

3. 'Ihe improvement in the art of converting hydrocarbons .for the production of a high anti'- knock gasoline, which comprises simultaneously 15 heating a butane distillate and a gas oil distillate in separate heating zones, heating the butane distillate in a stream of restricted cross section to a substantially higher temperature than that to which said gas oil distillate is heated to con- 30 vert the constituents of the butane distillate into unsaurated compounds, heating the gas oil distillate to a relatively high cracking temperature, heating said butane and said gas oil distillates in said streams for a suillcient time to produce a substantial proportion of active or nascent unsaturated hydrocarbons, but without substantially polymerizing the products oi said streams therein, mixing the products of said heating operation and subjecting the resulting mixture to a further l heating at a temperature of approximately 1040 F. for a substantial period ot time to interpolymerize the mixed products, conducting the resulting highly heated vapor products into an enlarged reaction zone in which the reaction is continued for a sumcient time to convert a substantial proportion of the products into constituents boiling within the gasoline range. and fractionating the resulting converted products to separate out a fraction containing the desirable high anti-knock Q' gasoline constituents.

4. The improvement in the art of converting hydrocarbons for the production of a high antiknock gasoline, which comprises simultaneously heating a butane distillate and a gas oil distillate in'separate vheating zones, heating the butane distillate in a stream of restricted cross section to a substantially higher temperature than that to which said gas oil distillate is heated to convert the constituents of the; butane distillate into u unsaturated compounds, heating the gas oil distillate to a relatively high cracking temperature, heating said butane and said gas oil distillates in said streams for a suillcient time to produce a substantial proportion oi active or nascent un- Il saturated hydrocarbons, but without substantially polymerizing the products oi said streams therein, mixing the products of saidheating operation and subjecting the resulting mixture to a further heating at a temperature of approxin mately 1040 F'. for a substantial period of time to interpolymerize the mixed products, conducting the resulting highly heated vapor product: into an enlarged reaction zone in which the reaction is continued for a sumcient time to convert a substantial proportion of the products into constituents boiling within the gasoline range, frac- 5.

tionating the' resulting products to recover a gas oil fraction higher boiling than the gasoline range and to separate the gasoline and lower boiling products as vapors. fractionating the separated gasoline and lower boiling hydrocarbons to separate out a stabilized gasoline and recover a butane fraction of lower boiling point than gasoline, and utilizing said recovered gas oil and butane fractions respectively of higher and lower boiling point than the gasoline range to supply at least in part the distillates subjected to heating in said separate heating zones.

5. The improvement in the art of converting hydrocarbons for the production of a high antiknock gasoline, which comprises simultaneously heating a butane distillate and a gas oil distillate Y in separate heating zones, heating the butane distillate in a stream of restricted cross section to a substantially higher temperature than that to which said gas oil distillate is heated to convert Athe constituents of the butane distillate into unsaturated compounds, heating the gas oil distillate to a relatively high cracking temperature, heating said butane and said gas oil distillates in said streams for a sufilcient time to produce a substantial proportion of active or nascent unsaturated hydrocarbons, but without substantially polyrnerizing the products of said streams therein, mixing the products of said heating operation and subjecting the resulting mixture to a further heating at a temperature of approximately 1040 F. for a substantial period of time to interpolymerize the mixed products, conducting the resulting highly heated vapor products into an enlarged reaction zone in which the reaction is con- 0 tinued for a sumcient time to convert a substantial proportion of the products into constituents boiling within the gasoline range, fractionating the resulting products to recover a gas oil fraction higher boiling than the gasoline range and u to separate the gasoline and lower boiling products as vapors, passing the vapors of the separated gasoline and lower boiling products in intimate contact with phosphoric acid in a refining zone to refine said vapor products, removing the 60 rened vapors from said reiining zone and iractionating them to separate out a stabilized gasoline and recover a butane fraction of lower bolling point than gasoline, and utilizing said recovered gas oil and butane fractions respectively of higher and lower boiling point than the gasoline range to supply at least in part the distillates subjected to heating in said separate heating zones.

DAVID G. BRANDT. I0 

